1. Field of the Invention
The present invention relates to a confocal microscope, more particularly to a confocal microscope which enables to programmably vary the number of illumination spots and the pinhole sizes.
2. Description of the Related Art
A confocal microscope is used to observe a sample by scanning an optical spot focused onto the sample and bringing fluorescent light or reflected light emanating from the sample into a focus to obtain an image. Confocal microscopes are used for observation of physiological reactions in living cells in the biological and biotechnological fields, observation of morphologies, and observation of surfaces of LSIs in the semiconductor industry.
FIG. 2 is a diagram showing a related art confocal microscope.
In FIG. 2, a confocal scanner 110 is connected with an aperture 122 of the microscope 120. Laser light 111 is collected into individual light beams by microlenses 117 in a microlens array disk 112. After passage through a dichroic mirror 113, the beams are transmitted through individual pinholes 116 in a pinhole array disk 114 (hereinafter, referred to as “Nipkow disk”) and are collected onto a sample 140 on a stage 123 by an objective lens 121 equipped to the microscope 120.
A fluorescent signal emanating from the sample 140 again passes through the objective lens 121 and is collected onto the individual pinholes in the Nipkow disk 114. The beams of the fluorescent signal passed through the individual pinholes are emitted from the confocal scanner 110 such that the beams are reflected by the dichroic mirror 113 and that the beams are collected onto an image sensor 131 via a relay lens 115. In this confocal microscope, the Nipkow disk 114 is rotated at a constant speed by a motor (not shown). Movement of the pinholes 116 caused by the rotation scans the focal points on the sample 140.
Since the plane at which the pinholes of the Nipkow disk 114 are arrayed, the surface of the sample 140 to be observed, and the photosensitive surface of the image sensor 131 are placed in an optically conjugate relationship, an optically sectioned image of the sample 140 (i.e., confocal image) is collected onto the image sensor 131 (see, for example, JP-A-5-60980).
JP-A-5-60980 is referred to as a related art.
In such a confocal microscope, there are about 1,000 pinholes within the field of view. It follows that 1,000 beams are illuminated simultaneously.
Only with this configuration, however, only information about multiple points is derived. Therefore, it is necessary to scan the laser beams in order to accept an image, i.e., planar information. Consequently, a two-dimensional image is constructed in 1 msec (at the highest speed) by rotating a Nipkow disk equipped with microlenses and raster-scanning a plurality of beams.
The related art confocal microscope described above uses the multi-beam scanning technique relying on individual pinholes in a Nipkow disk. In this Nipkow disk, the pinhole sizes are fixed. The illuminating light has a Gaussian distribution obtained by collimating diffused laser light. In principle, the light intensity is not uniform between the center and surrounding portions of the illuminating light. Rather, shading has occurred. Furthermore, the area of the Nipkow disk limits the number of beams hitting the sample and so there is the problem that the field of view is narrowed.